Along with the development of information and communication technology, various wireless communication technologies have been developed. Thereamong, wireless local area network (WLAN) enables users to wirelessly access the Internet through their portable terminals such as personal digital assistants (PDAs), laptop computers, and portable multimedia players (PMPs) in homes, offices, or specific service areas, based on wireless frequency technology.
To overcome limits to communication speed, which are a weakness of WLAN, systems for increasing speed and reliability of a network and extending wireless network coverage have been introduced in recent technology standards. For example, IEEE 802.11n supports a high throughput (HT) of a data processing rate of up to 540 Mbps or higher and adopts multiple input and multiple output (MIMO) technology in both a transmitter and a receiver in order to minimize transmission errors and optimize data rate.
As next-generation communication technology, machine-to-machine (M2M) communication technology has been discussed. Even in an IEEE 802.11 WLAN system, technology standard for supporting M2M communication has been developed as IEEE 802.11ah. A scenario in which devices occasionally exchange less data at low speed in an environment in which many devices are present may be considered in M2M communication.
Communication in the WLAN is performed by a medium shared between all devices. If the number of devices increases as in M2M communication, efficiency of a channel access mechanism needs to be improved in order to reduce unnecessary power consumption and interference.